This microbial transformation of organic matter in soil is mineralisation when organic carbon of organic substances is transformed to CO2 and from mineralised organic matter those mineral nutrients are released that were already contained in organic matter in mineral (ionic) form and those that were in it in organic form. CO2 is an important fertiliser in agriculture; it is the basic component for photosynthetic assimilation, for the formation of new organic matter produced by plants. As plants can take up only nutrients in mineral form (K+, NH+, NO3-, Ca2+, Mg2+, H2PO4-, HPO42-, SO42- etc.) and nutrients in organic form (e. g. protein nitrogen, phosphorus of various organophosphates), it is not accessible to plants, and besides its main function — energy production for the soil microedaphon — the mineralization of organic matter in soil is an important source of mineral nutrients for

plants. It is applicable solely on condition that organic matter in soil is easily mineralisable,

i. e. degradable by soil microorganisms.